Process of making rubber articles



Jame 24, 194-1. I RAFLQVICH 2,247,337

' Y PROCESS F MAKING RUBBER ARTICLES Filed Dc. 9, 1937 2 Sheets-Sheet 1 m: 4', 1941., v RAFLQVICH 2,247,337

PROCESS OF MAKING RUBBER ARTICLES Filed Dec. 9, 1937 'Z-SheetsShegg 2 may:

ATTQRNEYSW canization to one another Fatented June d, that tartar 23%,333 racemes or e auburn enriches Harry mafilovich, Detroit, Mich. lipplicationlllecember 9, llbttyberial No. 31%,935)

(Cl. le 53) 4 Clai.

ihis inventionrelates to a rubber article and process of making the same and while the process forming the subject of my invention can be used for making a wide range of rubber articles, the invention is illustrated a embodied in a toilet seat composed principally of rubber, vulcanlzed by heat and having a metal reinforcing member which also forms a part of the mean for hlnging the This application a continuation in part of my copendlng United States application for Process of mal -ring rubber articles, Serial No. 732,830, filed June 28, i934.

One of the objects of the invention is the production of such articles of greater uniformity of composition and superior properties and a greater ease and economy in manufacture.

Another object is a composition of matter for use in the manufacture of vulcanized blown rubber articles, which composition includes unvulcanized or raw rubber in solid form, preferably smoked sheet rubber and a blowing agent heretofore never used with rubber compositions that must be subjected to the relatively high tempera tures required to efifect vulcanization oi unvulcanized rubber by heat. This composition is simultaneously molded, blown and vulcanized by .the application of heatand may contain a high percentage of fillers as may be desired. The specific blowing agent employed in the heat volcanization process also permits more accurate control of the process.

Another object of the present invention is to provide a rubber article composed of a relatively soft sponge rubber core encased by an. integral rubber shell of densertexture, the use of the sponge rubber core reducing the amount of rubber employed and the weight of the article and also imparting resiliency and noiseless properties. The case or shell can be either made of hard rubber or can also be made or sponge rubber and if made of sponge rubber preferably has molding, has a smooth and shiny appearance without special polishing.

Another object of the invention is to provide such a sponge rubber core encased by a denser rubber in which the blowing of the core and the vulcanization of the core and case and their vulis accomplished by a simple molding operation.

Another object of the invention is to provide a rubber article and method or making the same in which any desired metallic reinforcement can be embedded in or applied, to the rubber before vulcanization and molding, the rubber vulcanizing to said metal reinforcement and a firm union being obtained therewith.

' dental escape of the blown rubber to the exterior of the article at extremities of the mold.

Another object of the invention is to provide such an article which is built up of unvulcanized rubber sheets, such sheets being readily cut to any desired form and being readily joined to one another to provide the blank.

Another object of the invention is to provide a method of molding rubber articles which. permits the sponge rubber core and the case to be located in any manner desired.

Another aim of the present invention is to provide a rubber article which can be produced in any desired color, particularly the more delicate or o-called pastel shades, thereby permit= ting articles, such as toilet seats, to be made to harmonize with other fixtures.

In the accompanying drawings:

. Fig. i is a perspective view of a rubber toilet seat blanl-z preparatory to its being placed. in a mold.

Fig. 2 is a vertical cross section through the two parts of a steam jacketed mold showing the blank in place therein.

Fig. 3 is a top plan view of a toilet seat embodying my invention.

Figs. 4-8 are vertical sections, taken on the correspondingly numbered lines on Fig. 2.

Fig. 9 is a view similar to Fig. 8 showing a modified form or my invention.

Figs. 10-13 are cross sections, through the mold used in carrying out a modified form. of my invention, Fig. 10 showing an unvulcanized sheet placed in a small core mold; Fig. 11 showing this core blown and partly vulcanized; Fig. 12 showing the blown and partly vulcanized core placed in a larger mold and encased in unvulcanlzed sheets of'rubber also having a blowing agent and Fig. 13 showing the finished article produced by the steps illustrated in Figs. 10-12.

The invention i illustrated in connection with a toilet seat having a rounded seat portion it and forwardly projecting horns or extensions ii and it although it will be understood that the invention can be carried out with a wide range of other rubber articles. At its rear the toilet seat is formed to provide a rearward extension is carrying the .means whereby the seat is hinged. In the form of the invention shown in Figs. 1-9, the toilet eat is composed of a soft sponge rubber core it which can be completely encased in a hard rubber shell or casing it, the core and shell being vulcanized to one another. If de-- sired sheets of insulating material, such as a sheet .orasbestos ll, can be incorporated in the seat near the top layer to impart heat insulating properties. In order to strengthen the toilet seat a metal reinforcing member indicated generally at E8 is embedded in the sponge rubber core, this reinforcing member comprising a metal plate arranged at the rear of the toilet seat and having flat arms i9 extending toward the horns ii and I2 and reinforced by ribs 20. At its rear this reinforcing member i8 is formed to provide a pair of bosse 25 carrying pins 26 each having a stop houlder 21 along one side. Each of these bosses 25 also carries a sleeve 28 embedded in the rubber and the pins 26 extend outwardlyfrom the sleeves 28 and are journaled in bearings 2% of fittings 30 secured to the rear of the water closet bowl (not shown). The fittings 30 can be suitably encased with rubber 3i for decorative purposes and each bearing 29 includes an extension 32 fitting into the corresponding sleeve 28 and engaging the stop shoulder 27 of the corresponding pin' 26. The stop shoulder 21 and 32 coact to limit the rearward movement-of the toilet seat.

The modified form of the invention shown in Fig. 9 is the same a that shown in Figs. 1-8 except that the hard rubber casing 35 only extends around the top of the sponge rubber core 35 instead of completely around this core, as shown in Figs. 1-8.

In making toilet seats in accordance with my invention it is desirable to make them of different colors to harmonize with the bathroom fittings. Heretofore it has been impossible to provide such colors except in'very dark shades and it is one of the objects of the invention to provide rub-. ber articles, such as toilet seats, of delicate or socalled pastel shades. The principal difiiculty is that with the high temperatures used in vulcanizing the rubber the light colors grey and are not stable. I have found that by employing zinc sulfide, whiting, magnesia or any other white filler, mineral rubber colors of delicate shades can be employed and will not grey during vulcanization. In making the composition for the hard rubber case formed as shown in Figs. 1-9 I prefer to employ the following ingredients:

Rubber (smoked sheet) pounds 25 Mineral rubber color do 8 Zinc sulfide, whiting, or magnesia do 8 Sulfur do 12%, Accelerator ounces 3 to 4 Oil pounds 1% In making black-or dark colored toilet seats additional fillers in the form of reclaimed rub-' 'ber can be employed as well as limestone and Rubber (smoked sheet) pounds 2 Yeast (commercial dry yeast) do 1 to 4 Soda (bicarbonate) do to 4 Petrolatum (Vaseline). ounces 4 to 12.

Oil (various mineral and vegetable) ..do 4 to 12 Sulfur (flowers) do 1 to 6 When the' master batch has been thoroughly mixed to a uniform homogeneous mass, a small a rees? amount, about one-quarter of the above, is incorporated with the following:

This produces a batch which is then rolled into a sheet and a blanklba cut therefrom. This blank is of the general shape of the blanks Isa and it!) but smaller and is sandwiched between the blanks 15a and ltb, as illustrated in Fig. 1, overlaying the reinforcing member l8. In order to secure greater pressure against the reinforcing member l8 and a firm union therewith, an additional small blank 15b is placed over the blank I511 where this blank i5a overlays the reinforcing member l8, as best illustrated in Figs. 4, 5 and 6.

If heat insulating properties are desired the sheet of asbestos I1 is provided. This sheet is of the same general shape'as the toilet seat and is interposed between the layers Ma and I5!) which form the sponge rubber core and the top sheet [617 which forms the top of the shell.

In order to prevent. the blank l5a from flowing to the exterior of the seat at the extremities H and I2 of the toilet seat, means are-preferably provided for confining the sponge rubber at these places. These means comprise small pieces of cloth 31 which are wrapped around the extremities of the sheet [5a, as best illustrated in Figs. 1 and 7. After the blank is built up as shown in Fig. 1, the edges of the sheets Ilia arid lBb are pressed together, as ,best illustrated in Fig. 2, these sheets being quite tacky. The blank is then placed in a mold composed of a lower relatively flat section 40 which is steam jacketed, as indicated at 4!, and an upper section 42 which is steam jacketed, as indicated at 43. These mold sections, of course, conform interiorly to the desired external form of the toilet seat and are held together in any suitable manner. Steam at or pounds pressure is then introduced into the jacketed mold sections and the vulcanization proceeds for from one hour to an hour and twenty minutes. During this period the yeast in the sponge rubber core develops carbon dioxide and forms the sponge rubber core l5, this core expanding under the blowing action of the yeast and forcing the sheets Ilia and lGb against the mold faces. At the same time vulcanization of both the sheets i511, l5b and the sheets lfia and iGb takes place and the sponge rubber core is intimately united with the hard rubber exterior. During the vulcanization process, the metal reinforcing member I8 is firmlymunited to the rubber so that the resulting toilet seat is a unitary bonded structure. After the vulcanization is complete the core sections are separated and the completed toilet seat removed, the delicate mineral colors employed being unaffected by the vulcanizing temperature and the sponge rub-' ber core being completely encased by the hard rubber shell.

In the form of the invention shown in Fig. 9 the same process is carried out except that the lower sheet I60. is not employed.

In Figs. 10-13 is illustrated a form of the invention which differs from the form shown in Figs. 1-9 inthat the casing, as well as the core, 1s made of sponge rubber. For this purpose the core is first molded in a small form and then placed in the full sized form surrounded by the sheets of rubber which form the casing. Such a seat has the advantage of additional lightness and it has also been found that the finished article comes out of the final mold with a dense and shiny surface, thereby eliminating the necessity of polishing the article. In Fig. is illustrated the upper and lower sections M1 and ll of the core mold. In this mold is placed a sheet 32 of the core material, this being made of the same composition as the core material for the form of the invention shown in Figs. l9. The mold is then closed and subjected to a blowing and partial vulcanization treatment at 75-430 pounds steam for approximately minutes. This length of time is not suflicient to permit complete vulcanization of the core. However, the core has been blown sumciently to fill the mold sections M and M, as illustrated in Fig. 11. in this condition the core is removed.

In encasing the core a full sized mold is em-- ployed, the sections of which are indicated at M and These sections are lined with sheets db and dd oi unvulcanized rubber, The composition of the sheetsdd and do is the same as the composition of the core rubber used in providing the core it in the form of the invention shown in Figs, 1-9 except that approximately 30% more blowing agent, the yeast, has been added both to the master batch and also to the added batch.

After the core sections it and M have been so 7 lined the partially finished sponge rubber core n is covered with a suitable rubber cement ll, to secure good adhesion and is placed in the core sections 53, M surrounded by the sheets 55 and lid which form the casing. The mold sections 433 and dd are then closed and subjected to the same heat, 1. e. 75-80 pounds steam pressure, for a period of approximately an hour and a quarter. During this period the vulcanization of the core M is completed and this core is also vulcanized to the casing sheets and d5. At the same time the blowing agent iii-these casing sheets 65 and illi efiects a porosity in the casing but since the molding is carried on at higher pressure and a greater quantity of blowing agent is used, the pores of the casing are very much finer than the pores already formed in the core 32. It has also been found that the surface of the casing sheets tit, db, when removed iroin the mold, are dense and non-porous and have a high finish, requiring no further processing.

In carrying out the invention, where the article is of uniform composition throughout and hence made from a single portion or a batch or uniform composition it is generally desirable to carry out the invention by using such an amount as will only partially fill the mold cavity and to I then subject the mold to a preliminary heating with the mold opened or closed. After a predetermined period, determined by several factors, the mold is closed tightly and the finish heat is given. 7

The temperature preferred during the preliminary heat is in the neighborhood of 240 F. and, depending upon the size of the mold, this heating is carried on for a longer time, say 45 minutes, and at a temperature of around 350 F. As a general rule lower temperatures lengthen and higher temperatures shorten the curing time.

From the foregoing it will be seen that the present invention provides a rubber article composed of a denser rubber shell intimately bondedto a sponge rubber core thereby securing the advantage of a smooth, hard and strong surface and at the same time obtaining resilience and noiseless properties through the sponge rubber core. Because of the sponge rubber core the article is also of lighter weight and, if desired, a porous casing can be provided to make it still lighter in weight, and is less expensive and the article can also have heat insulating properties by the provision of the asbestos sheet ll. It will also be seen that the invention permits of the use of delicate or pastel coloring material without greying thereof and that the process f lends itself to production methods,

I claim as my invention:

1. The method of making a rubber article which comprises preparing a partly vulcanized sponge rubber core, applying an unvulcanized rubber cover containing a blowing agent to said core, placing said assembly in a mold and applying heat to complete the vulcanization and blowing of said core and cover.

2. The method of preparing a hard rubber ar ticle which comprises preparing a sheet having a blowing agent and a large amount of vulcanizing agent therein, cutting said sheet to provide a blank oi the general shape of the article, applying a small mold to confine said blank, applying heat to said mold to partially vulcanize and partially blow a core having the shape of said mold, removing said partly blown and vulcanized core mm said small mold,applying an unvulcanized rubber cover to said partly vulcanized and partly blown core, placing said covered core in a large mold having the shape of the article to be produced, and applying heat to said large mold to complete the vulcanization and blowing of said core and the vulcanization or" said cover. 3. The method of preparing a hard rubber article which comprises preparing a sheet having a blowing agent and a large amount of a vulcanizing agent therein, cutting said sheet to provide a blank of the general shape of the article, applying a small mold to confine said blank, applying heat to said mold to partially vulcanize and partially blow a core having the shape or said mold, removing said partly blown and vulcanized core irom said small mold, cementing an unvulcanized rubber cover to said partly vulcanized and partly blown core, placing'said covered core in a large mold having the shape of the article to be produced, and applying heat to said large mold to complete the vulcanization and blowing of said core and the vulcanization of said cover.

4. The method of preparing a hard rubber article which comprises preparing a sheet having a blowing agent and a large amount of a vulcanizing agent therein, cutting said sheet to provide a blank of the" general shape of the article, applying a small mold to confine said blank,

applying heat for about fifteen minutes to said HARRY RAFLOVICH. 

